Vienna Gambit, with Max Lange Defense

The Vienna Gambit with the Max Lange Defense arises when White answers 2...Nc6 with 3. f4. The name Vienna Gambit traditionally belongs to this position, though online it is often applied to 2...Nf6 3. f4 as well. White develops the queen's knight first and only then attacks e5 with the f-pawn, so the gambit resembles a deferred King's Gambit. With the knight on c6 rather than f6, Black has no quick ...d5 counterstrike, but also no knight for e5 to chase, so taking the pawn is a serious option. The engine gives Black a slight edge. In practice White scores well, and draws are rare.

Acceptance with 3...exf4 is the most common reply. Once the e5-pawn is gone, White's d-pawn can reach d4 without obstruction, and a later d5 drives the c6-knight to a poor square. The Knight Variation, 4. Nf3, is the main continuation. After 4...g5 the play takes on a King's Gambit character. In the Hamppe-Allgaier Gambit, 5. h4 g4 6. Ng5, White offers the knight. The Kieseritzky-style 6. Ne5 is unavailable here because the c6-knight controls e5, although that knight does little to help the defense after 6. Ng5. The Hamppe-Muzio Gambit, 5. Bc4 g4 6. O-O, usually continues 6...gxf3 7. Qxf3, with a knight given up for an attack on the black king; 7...Ne5 8. Qxf4 Qf6 is the Dubois Variation. The Pierce Gambit, 5. d4, normally goes 5...g4 6. Bc4 and can also arise from 4. Nf3 g5 5. Bc4 g4 6. d4. Black's main alternative on move five is 5...d6. A quieter treatment of 4. Nf3 is the Cunningham Defense, 4...Be7.

The Steinitz Gambit, 4. d4, lets Black check with 4...Qh4+ 5. Ke2. White bets that the pawn center and the exposed black queen outweigh the displaced king. Wilhelm Steinitz favored the line, but it has largely disappeared from modern practice.

Black can also decline. The second most common reply is 3...d6, which supports e5 and is one of the engine's preferred moves. The position after 3...Nf6 is identical to 2...Nf6 3. f4 Nc6, which is considered dubious because of 4. fxe5 Nxe5 5. d4, when e5 follows with a strong attack; of the frequent replies, White scores best against it. The Quelle Gambit, 3...Bc5 4. fxe5 d6, reverses the roles and has Black give up a pawn for rapid development and pressure on the a7-g1 diagonal.